It is expected that a sensing device for sensing a specific functional group present in a fluid will be widely applied in the field of biosensors sensing the presence or absence of an amino acid or a DNA molecule in a body fluid.
Recently, there has been a rapid movement to develop a new technological base by converging Information Technology (IT) and Nano Technology (NT), which have heretofore been independently developing, with Biotechnology (BT). Particularly, in a nano-biochip field that is one of nano-bio (NT-BT) convergence technology, a biosensor for sensing protein in a blood is actively studied.
In the nano-biochip field, various methods for sensing, analyzing and quantifying a specific bio material are developing. Among these methods, a method of sensing a specific bio-material by fluorescence labeling is typical. This method is widely applied in currently-available DNA chips.
However, the fluorescence labeling method is difficult to apply to various materials because it requires an additional bio-chemical preparation step of a test sample such as blood or saliva in order to sense a specific bio-material.
For example, in the case of protein labeling, about 50% of functional protein is in-activated during an unspecific labeling process. Accordingly, only a very small amount of analyte is available for the purpose.
For this reason, biosensors based on silicon, which improve sensitivity or reproducibility and are capable of being mass-produced using a semiconductor process, have been introduced.
For example, a biosensor having high-sensitivity and capable of sensing a specific material using a silicon nano wire (Si-nano wire) formed by a CVD growth technique in a bottom-up approach has been widely studied in recent years, however a study on a Si-nano wire biosensor capable of being mass-produced using an industrial CMOS manufacturing process, which is easily implemented and ensures reproducibility in a top-down approach is more actively progressing.
In addition, many study results on an ion-sensitive field effect transistor (ISFET) having a field effect transistor (FET)-type device and also using a CMOS process have been disclosed.
The ISFET is similar to a nano wire biosensor in an aspect of changing conductivity of the sensor by increasing a surface charge by interaction between a target molecule in a solution and a probe molecule of a sensor. However, it is characterized in an aspect of having a common field effect transistor structure and determining a gate voltage according to a target molecule adsorbed to a top of a gate, the gate voltage corresponding to a pattern of an operating characteristic curve of a transistor.
However, it is difficult to make a wide variation of the total gate voltage due to a variation in amount of charge generated by interaction between the probe molecule and the target molecule, and thus sensitivity of the device is significantly decreased.